Effect of impurities on thermal stability of pseudomorphically strained Si:C layer

We investigate the thermal stability of pseudomorphically strained Si:C layer using high resolution x-ray diffraction (HRXRD) and Fourier transform infrared (FTIR) spectroscopy. Far below β-SiC precipitation threshold, almost complete strain relaxation is found without significant substitutional carbon (Csub) loss. FTIR shows the strain relaxation is related to volume compensation by Csub-interstitial complex formation through oxidation injection of interstitial. By multilayer HRXRD kinematical simulation, we find correlation of the enhanced strain relaxation to P distribution, implying P’s role as additional interstitial promoter during postannealing treatment. We relate our findings to recent reports on strain relaxation issues in Si:C devices fabrication.